National Instruments NI 5401 Figure2 -8 shows the essential block diagram of analog waveform generation.

Chapter 2 Function Generator Operation
NI 5401 User Manual 2-8 www.natinst.com
Figure2 -8 shows the essential block diagram of analog waveform
generation.
Figure 2-8. Analog Output and SYNC Out Block Diagram
Figure2 -9 shows the timing relationships of the trigger input and
waveform output. Td1 is the pulse width on the trigger signal. Td2 is the time
delay from trigger to output on Arb output. Refer to Appendix A,
Specifications, for more information on these timing parameters.
Figure 2-9. Waveform and Trigger Timings
Note You can switch off the analog lowpass filter at any time during waveform generation.
When you change this setting, the bouncing of electromechanical relays on the NI 5401
distorts the output signal for about 10ms.
DAC
Gain
DAC
Pre Amp Main Amp
Filter
Lowpass 10 dB
Attenuator Attenuators
Output
Enable
25 ΩArb
Selector
50 Ω/75 Ω
Offset
DAC
12
Clock
Level
DAC
+
-
SYNC
Comparator
50 Ω
50 Ω
(63 dB in 1 dB steps)
Trigger Input Signal
(Slope: Positive, TTL)
Waveform Output
(±5 Vpp into 50Ω)
Td1
Td2